Mono Audio Upmixing via Compression Residual Ambient Extraction
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Solution Overview
Problem
Existing methods for upmixing mono audio signals to multi-channel systems often require additional information and introduce synthetic audio effects, failing to effectively separate ambient signals from direct sounds, especially when processing one-channel signals.
Innovation Solution
The method involves lossy compression of an audio signal to generate a compressed representation, calculating the difference between the original and compressed representations to extract the ambient signal, and using this difference as the basis for creating a multi-channel audio signal, specifically for rear loudspeakers, while the original signal is used for front loudspeakers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If lossy compression is applied to extract ambient signals, then ambient signal extraction capability is improved, but audio quality loss occurs
Solution Approach 1:
The patent extracts ambient signals by taking out the difference between original and lossily compressed audio signals. The lossy compression removes certain frequency components and temporal details, and by calculating the difference (residual) between original and compressed signals, the ambient signal is isolated. This allows ambient signal extraction without requiring additional microphones or information sources.
Solution Approach 2:
The patent changes audio signal parameters through lossy compression, specifically modifying frequency domain representation and temporal resolution. By adjusting compression parameters and analyzing the residual differences, the method identifies ambient signal characteristics while managing the trade-off between extraction capability and audio quality preservation.
2Adaptability or versatility
If mono audio signals are upmixed to multi-channel signals, then spatial audio experience is improved, but signal processing complexity increases
Solution Approach 1:
The patent segments the audio signal processing into distinct stages: lossy compression, difference calculation, ambient signal extraction, and multi-channel distribution. By dividing the upmixing process into modular segments, the system manages complexity while achieving spatial audio effects. Each segment handles a specific aspect of the transformation from mono to multi-channel.
Solution Approach 2:
The patent creates a universal upmixing process that can handle various types of mono audio signals and output them to different multi-channel configurations. The same core algorithm (lossy compression + difference calculation) serves multiple functions: ambient signal extraction, spatial distribution, and adaptation to different loudspeaker setups, reducing overall system complexity.
3Quantity of substance
If ambient signals are extracted from mono signals, then rear channel audio content is improved, but separation precision of direct sounds from ambient sounds decreases
Solution Approach 1:
The patent uses lossy compression as an intermediary process to facilitate ambient signal extraction. The compression algorithm acts as a mediator that selectively removes certain signal components, and the residual difference between original and compressed signals serves as the extracted ambient signal. This intermediary approach enables separation without requiring direct analysis of the original signal's ambient components.
Data Source
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AI summary
An apparatus for generating an ambient signal from an audio signal comprises means for lossy compression of a representation of the audio signal so as to obtain a compressed representation of the audio signal describing a compressed audio signal. The apparatus for generating the ambient signal further comprises means for calculating a difference between the compressed representation of the audio signal and the representation of the audio signal so as to obtain a discrimination representation. The apparatus further comprises means for providing the ambient signal using the discrimination representation. An apparatus for deriving a multi-channel audio signal from an audio signal comprises an apparatus for generating an ambient signal from an audio signal, an apparatus for providing the audio signal as a front-loudspeaker signal and an apparatus for providing the ambient signal as a back-loudspeaker signal.